ProtonMail email text font boost and coloration. Simple, easy on the eyes.

protonmail-theme-mono-contrast.css

/* ProtonMail theme adjustment: Monospace and Higher Contrast Email Text
   Send feedback: t0dd@protonmail.com

   Note: This changes email's plain text *appearance*. It does not
   actually change the text formating. If the text is formated in
   the email and you accept HTML... those settings override ours.
*/
/*
I like keeping options around...
@import url(https://fonts.googleapis.com/css?family=Roboto+Mono:400,400italic,700,700italic);
@import url('https://fonts.googleapis.com/css?family=Exo+2');
@import url('https://fonts.googleapis.com/css?family=Comfortaa');
@import url('https://fonts.googleapis.com/css?family=Space+Mono');
@import url('https://fonts.googleapis.com/css?family=Roboto+Mono');
@import url('https://fonts.googleapis.com/css?family=Source+Code+Pro');
*/
@import url('https://fonts.googleapis.com/css?family=Droid+Sans+Mono');

.email {
    /*
    font-family: 'Exo 2', sans-serif;
    font-family: 'Comfortaa', cursive;
    font-family: 'Space Mono', monospace;
    font-family: 'Roboto Mono', monospace;
    font-family: 'Source Code Pro', monospace;
    */
    font-family: 'Droid Sans Mono', monospace;

    /* http://www.uxmatters.com/mt/archives/2007/01/applying-color-theory-to-digital-displays.php */
    /*color: #000;*/ /* Black */
    /*color: #333;*/ /* Charcoal Gray */
    color: #330000;  /* Burnt Umber (the inverse of Amber, #FFBF00) */


    /*background-color: #FFF;*/ /* White */
    /*background-color: #F8F8FF;*/ /* Ghost White */
    font-size: 125%; /* I'm old */
}

.frame {
    /*background-color: #FFF;*/ /* White */
    /*background-color: #F8F8FF;*/ /* ghost white */
}